1. Field of the Invention
The present invention relates to a driving apparatus, a light source driving apparatus, a light source apparatus, a projection apparatus, and a driving method, suitable for driving a load in which the value of a physical quantity as a controlled object periodically changes.
2. Description of the Related Art
A projection apparatus of a time division (field sequential) scheme projects a color picture by sequentially and repeatedly irradiating display elements with red light, green light, and blue light. There is considered a technique of using three types of light-emitting diodes (LEDs) as light sources which emit the respective primary color light beams described above and sequentially and repeatedly lighting the LEDs using an output from one DC/DC converter by a switching unit. In this case, according to Jpn. Pat. Appln. KOKAI Publication No. 2008-234842, since the LEDs of the respective colors differ in drive voltage, the DC/DC converter changes a drive voltage in synchronism with the start of lighting of each LED.
An output from an AC/DC converter is supplied to the above DC/DC converter. Since the output voltage of the DC/DC converter does not become stable unless the output voltage of the AC/DC converter becomes stable, it is conceivable to incorporate a stabilization circuit in the AC/DC converter. If the stabilization circuit incorporated in the AC/DC converter is of a switching scheme, it is preferable, for the purpose of reducing the number of components, to control the stabilization circuit and the DC/DC converter by using one controller. When the stabilization circuit and the DC/DC converter are controlled by one controller in this manner, in particular, as the output voltage of the DC/DC converter changes, a response delay tends to occur in the output voltage of the stabilization circuit from the viewpoint of a control cycle. For this reason, when the output voltage of the DC/DC converter changes because of the switching ON/OFF of the load, the pulsation (glitch) in the output voltage of the stabilization circuit increases. With this increase in pulsation, the pulsation in the output voltage of the DC/DC converter undesirably increases.
The present invention has been made in consideration to the above situation. It is an object of the present invention to provide a driving apparatus which can reduce the pulsation generated as a physical quantity as a controlled object periodically changes, a light source driving apparatus, a light source apparatus, a projection apparatus, and a driving method.